Moved the VM’s to different Laptop, problems got resolved.
I think the Processor was not compatible to run VM’s i think.
Also one problem i find is enabling EFI mode in virtual box always throws error d404479a-1b02-41f4-a7ab-407e52b807fa-image.png
Works fine without EFI mode.
Also in dhcp service enable the policy as Fog suggestions.
Now Overall Fog server setup completed. Successfully deployed images to all models of Laptops.
Thank you